The primary function of pulmonary surfactant is to reduce the surface tension (ST) created at the air-liquid interface in the lung. Surfactant is a complex mixture of lipids and proteins and its function is influenced by physiological parameters such as metabolic rate, body temperature and breathing. In the microchiropteran bat Chalinolobus gouldii these parameters fluctuate throughout a 24 h period. Here we examine the surface activity of surfactant from warm-active and torpid bats at both 24°C and 37°C to establish whether alterations in surfactant composition correlate with changes in surface activity. Bats were housed in a specially constructed bat room at Adelaide University, at 24°C and on a 8:16 h light:dark cycle. Surfactant was collected from bats sampled during torpor (2535°C). Alterations in the lipid composition of surfactant occur with changes in the activity cycle. Most notable is an increase in surfactant cholesterol (Chol) with decreases in body temperature [Codd et al., Physiol. Biochem. Zool. 73 (2000) 605-612]. Surfactant from active bats was more surface active at higher temperatures, indicated by lower STmin and less film area compression required to reach STmin at 37°C than at 24°C. Conversely, surfactant from torpid bats was more active at lower temperatures, indicated by lower STmin and less area compression required to reach STmin at 24°C than at 37°C. Alterations in the Chol content of bat surfactant appear to be crucial to allow it to achieve low STs during torpor. © 2002 Elsevier Science B.V. All rights reserved.
|Number of pages
|Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
|Published - 30 Jan 2002
- Surface activity